Essential oils are volatile oils obtained from plant or animal sources and are composed of complex mixtures of several constituents, such as monoterpenes and sesquiterpene hydrocarbons, monoterpene and sesquiterpene alcohols, esters, ethers, aldehydes, ketones, oxides and the like. These essential oils and their isolated constituents are frequently utilized as fragrance and flavor agents, and have been widely used in folk medicine for wound healing properties.
Scientific research has corroborated the beneficial effects of essential oils. Essential oils of eucalyptus have been found to “possess central and peripheral analgesic effects as well as neutrophil-dependent and independent anti-inflammatory activities” (Silva et al., 2003, J. Ethnopharmacol. 89(2-3); 277-283), and similar activity has been observed in essential oils from Lavendula angustifolia Mill. (Hajhashemi et al., 2003, J. Ethnopharmacol. 89(1):67-71). Essential oils have been demonstrated to exhibit antibacterial (Bezic et al., 2003, Phytother. Res. 17(9:1037-1040; Goren et al., 2003, Z. Naturforsch. 58(9-10):687-690; de Abreu Gonzaga et al., 2003, Planta Med. 69(8:773-775; Valero and Salmera, 2003, Int. J. Food Microbiol. 85(1-2): 73-81) and antifungal (Paranagama et al., 2003, Lett. Appl. Microbiol. 37(1):86-90; Shin, 2003, Arch. Pharm. Res. 26(5):389-393; Velluti et al., 2003, Int. J. Food Microbiol. 89:145-154) activities. Virucidal activity of essential oils has also been observed, including direct virucidal effects against Herpes simplex viruses types 1 and 2 (Garcia et al., Phytother. Res. 17(9):1073-1075; Minami et al., 2003, Microbial Immunol. 47(a):681-684; Schuhmacher et al., 2003, Phytomedicine 10:504-510).
United States Patent Application Publication No. 20050048139 by Modak et al., published Mar. 3, 2005, relates to topical compositions comprising an emollient solvent and an essential oil, which may further comprise additional additives, among which citric acid, glycolic acid and lactic acid are cited. It does not recognize the synergistic activity between essential oils and fruit acids nor does it disclose the concentrations of fruit acids to be used to provide a synergistic effect.
U.S. Patent Application Publication No. 20050019431 by Modak et al., published Jan. 27, 2005, relates to compositions comprising a quaternary ammonium compound and an essential oil (or active component thereof).
A number of patent applications relate to compositions comprising an essential oil (or component thereof) where zinc salts are added to inhibit irritation associated with essential oils. Examples of such patent applications include United States Patent Application Publication No. 20040102429 by Modak et al., published May 27, 2004 and United States Patent Application Publication No. 20050238602 by Modak et al., published Oct. 27, 2005.
U.S. Pat. No. 6,858,317 by Aamodt et al., issued Feb. 22, 2005, relates to methods for protecting wood from mold and sapstaining fungi which employ a non-toxic mold inhibitor which may be a plant extract such as an essential oil.
U.S. Pat. No. 5,100,652 by Kross et al., issued Mar. 31, 1992, relates to low concentration chlorous-acid generating oral hygience compositions which may comprise an essential oil as a flavoring agent.
U.S. Pat. No. 5,310,546 by Douglas, issued May 10, 1994, relates to a mouthrinse preparation comprising hydrogen peroxide, zinc chloride, sodium citrate, sodium lauryl sulfate, citric acid and ethanol and optionally an essential oil which is a denaturing agent.
BiON offers several skin care products comprising citric acid, botanicals, and other agents for topical use (San Diego, Calif., US).
Johnson et al. (U.S. Pat. No. 6,319,958 and US20020165130) relates to the use of sesquiterpenoids to promote uptake of exogenous antimicrobial compounds. Similarly, a related article discloses the use of sesquiterpenoids, such as nerolidol, farnesol, bisabolol and apritone, in enhancing bacterial permeability and susceptibility to exogenous antimicrobial compounds, suggesting that sesquiterpenoids have a non-specific and general effect (Brehm-Stecher et al. 2003, Antimicrobial Agents and Chemotherapy, 47(10):3357-3360). In particular, Brehm-Stecher et al. report that nerolidol, farnesol, bisabolol and apritone enhanced the susceptibility of S. aureus to the antibiotics erythromycin, gentamicin, vancomycin, ciproflaxin, clindamycin, and tetracycline.
U.S. Pat. No. 4,867,898 by Spaulding et al., issued Sep. 19, 1989, relates to a liquid hard surface cleaner comprising pine oil and organic, oil-soluble acids at a pH from 0-6.
U.S. Pat. No. 6,753,305 by Raso and Caselli, issued Jun. 22, 2004, relates to a hard surface disinfectant comprising up to 20 percent of cinnamon oil or a component thereof, 0.01-5 percent of an organic acid, and optionally an additional essential oil.
International Patent Application Publication No. WO2007/077573 by Mukhopadhyay, published Jul. 12, 2007, relates to antimicrobial compositions comprising an antimicrobial agent, such as triclosan, and a functionalized hydrocarbon, where the functionalized hydrocarbon can be an essential oil, and/or a solvent.
There is a continuing desire for an antimicrobial composition that is non-irritating, safe, and effective for repeated use in various professional and non-professional settings.